When Polaroid SX-70 film was still available, I used to create and sell hand-manipulated Polaroids.  You accomplish this effect by pressing on the tough top layer and that moves the pigment layer beneath it. Doing so gives it a gorgeous watercolor look. Then I photographed the Polaroids and applied the same software techniques to them as my HDR photography. 

Note: if you order these, you will not get a Polaroid. You will get an archival print. That is a good thing. Actual Polaroids are only 3" x 3".